The present invention relates to a system and method for spatial localization of an invasive device in Magnetic Resonance Imaging (MRI). More particularly, the invention relates to a system and method for tracking an invasive device during MRI imaging.
MRI provides visual information about the interior of a subject which can be very useful for surgical procedures. Using MRI, surgical tools such as interventional devices, also known as invasive devices, can be used to minimize the size of incisions resulting in shorter recovery times. The use of small incisions requires the invasive devices to be guided or tracked since they cannot be directly observed within the subject. MR-guided device tracking has generated considerable interest as a result.
One key component of current tracking methods is the ability to automatically define an appropriate MRI imaging scan plane. Optical navigational systems have been developed to provide interactive scan plane selection by measuring the position of reflective materials mounted onto the surface of a rigid interventional device. Optical tracking systems have limitations including requiring a line-of-sight between the markers and the detection system. This hinders positioning of the detection systems within the scan room which in turn restricts the range-of-motion of the physician during the procedure. Also, these optical detection systems add additional, and potentially expensive, components to an already congested physical environment and they require calibration between the tracking system and the MRI coordinate frames.
An improved wireless tracking method was recently developed using inductively coupled tuned fiducial markers, a limited projection reconstruction sequence (LPR-FISP), and a fast localization algorithm to provide automatic scan plane selection for interventional procedures. This tracking method improved upon optical tracking systems by providing fast, automatic scan plane selection without a line-of-sight requirement between the markers and the detection system. Unfortunately, this system of fiducial marker contrast using tuned coils is dependent on the position and orientation of the marker coil with respect to the transmitter and receiver coils. In certain orientations, this dependence can result in attenuation of the marker signal and a loss of tracking function. It is desirable to provide a wireless tracking system and method to track markers which reduces the dependency of the signal strength on the position and/or orientation of the marker.